HLA typing plays important roles in analyzing histocompatibility for organ transplants and determining an individual's susceptibility to certain diseases. Kidney transplants are frequently performed in Japan and it has been reported that the organ transplantation from related donors (e.g. family member) gives better survial of transplanted organ than that from unrelated donors, even though the HLA matching between a recipient and an unrelated donor is maximized by serologic HLA typing. This fact suggests that there may be some HLA subtypes that are not identifiable by the conventional serologic typing, or the influences by other unknown genes closely linked to the HLA, which controls success or failure of transplants (Yamamura, K., Yoshi, T., Metabolism Highlight, Metabolism 25: 373-380 special ed, Nakayama book, Tokyo).
In serological typing, antiserum of known specificity is added along with complement to lymphocytes to be tested for cytotoxicity. Although serological typing is easy to perform, a subtle difference of an antigen determinant is not identified and thus the presence of subtypes can be often overlooked. Nevertheless, an organ supply of unrelated donors has steadily increased so a new method of testing histocompatibility has been awaited.
HLA antigens are classified into two types, class I and class II. It is suggested that class II antigens DR, DQ and DP are essential for successful kidney transplants. Particularly, DR antigens expressed at the surface of various cells of the body play a key role in histocompatibility (Amamiya, H., Sada, M., Aizawa, H., Composition and function of HLA-D region in Research Report (1984), Statistics of kidney transplants and histocompatibility, the research is supported by Science research fund, 1983 (Comprihensive Research A).
DRw14, a type of known HLA-DR types, is the most difficult type to be defined serologically due to the poor availability of specific antisera. Nucleotide sequence analyses have shown that DRw14 has two subtypes, DRB1*1401 (DRw14-Dw9) and DRB1*1402 (DRw14-Dw16), as clasified by cellular HLA typing. (Bodmer, W. F., Albert, E., Bodmer, J. G., Dausset, J., Kissmeyer-Nielsen, F., Mayr, W., Payne, R., Rood, J. J., van, Trnka, Z., and Walford, R. L., 1984, Histocompatibility Testing p4-8, Springer-Verlag, Berlin; Tiercy, J.-M., Gorski, J., Betuel, H., Freidel, A. C., Gebuhrer, L., Jeannet, H., and Mach, B., 1989, J. Hum Immunol 24: 1-14; Gorski, 1989, J. Hum. Immunol 24: 145-149; Kao, H. T., Grgersen P. K., Tang, J. C., Takahashi, T., Wang, C. Y., and Silver, J. 1989, J. Immunol 142:17-43).
Organ transplantation between recipients and donors who are serologically compatible but incompatible with respect to subtypes of DR antigen from each other will cause some problems leading to graft rejection. Thus, serological typing alone may not be clinically useful for organ transplantation.
An object of the present invention is to overcome these disadvantages of serological typing. The invention provides reagents for the HLA-DR typing at the DNA level. More specifically, the invention provides oligonucleotide probes capable of identifying subtypes of a HLA-DR antigen precisely and reagents which include the oligonucleotide probes. Furthermore, the invention provides a method of detecting the HLA-DR subtypes.